1. The structure of the essay is not clear. I suggest you build a template for TOEFL essay writing and put every topic in this template. The structure of essay will improve dramatically;
2. As Jiang said, pay more attention to odd / plural numbers;
3. So many sentence are in Chinglish style. That means when you write this eaasy you translate Chinese into English. This is a bad habbit for all non-native writers. Try to avoid it;
4. Too many paragraphs.